WO 01/00539 A2 discloses a ceramic thermal insulation material for high-temperature applications. The material is developed in such a way that a thermal coefficient of expansion is adapted to that of a metal so that, when applying the ceramic material in the form of a coating on a metallic basic body, there are only limited thermal stresses owing to a different thermal expansion. For this purpose, the ceramic material has between 10 and 95 percent by weight magnesium aluminate (MgAl2O4) MgAl spinel, between 5 and 90 percent by weight magnesium oxide (MgO) and up to 20 percent by weight aluminum oxide (Al2O3). Granules of magnesium oxide are also embedded in a magnesium aluminate matrix. It is embodied in such a way that the magnesium aluminate must exist as a homogeneous matrix that does not exist as sintered-together magnesium aluminate granules with intermediate cavities, but as homogeneous pore-free magnesium aluminate. In this structure, the magnesium aluminate is sufficiently thermally stable to also preserve a casing enclosing the magnesium oxide during the process of thermal spraying. In this way, the area of the magnesium oxide remains enclosed during thermal spraying and the magnesium oxide cannot sublimate or evaporate. The application of the ceramic component is provided in a high-temperature fuel cell where a very impervious, non-porous ceramic layer must be used to prevent gas losses.
WO 98/26110 discloses a thermal insulation layer for high-temperature applications especially in gas turbine blades. Such gas turbine blades are exposed to particularly high temperatures and at the same time subjected to high thermal stresses. Therefore, these gas turbine blades are often made of a nickel, cobalt or an iron base superalloy that has special strengths at high-temperatures. The gas turbine blades are also cooled via an internal cooling system by means of cooling air. The gas turbine blades are also protected via a protective layer system that consists of a metallic corrosion protective layer to which a ceramic thermal insulation layer has been applied. A typical metallic corrosion protective layer is, for example, a layer of the base alloy MCrAlY, that not only fends off corrosive attacks on the basic body, but also acts as an adhesion agent for the ceramic thermal insulation layer. A particular problem is a thermal alternating load because the ceramic thermal insulation layer has different thermal expansion coefficients compared to those of the metallic basic body or the metallic corrosion protective layer that leads to thermal stresses. On the other hand, this significantly limits the service life because failure of the ceramic thermal insulation layer because of peeling off determines the service life of the gas turbine blade. Conventional thermal insulation layers on a zirconium dioxide base that are usually phase-stabilized with yttrium oxide can sometimes be replaced with new ceramics that are ternary oxides and have a pyrochlore or perovskite structure. Typically, ceramic thermal insulation layers are applied by atmospheric plasma spraying or electron beam evaporation.